Insulator



Dec. 17, 19 29. K. A. HAWLEY' 3 INSULATOR' inventor [fa/n A. Haw/y Patented. Dec. 17, 1929 UNITED STATES PATENT OFF-ICE KENT A. HAWLEY, OF BALTIMORE, MARYLAND, ASSIGNOR TO LOCKE INSULATOR CORPORATION, oFiBALTIMORE, MARYLAND, A CORPORATION OF MARYLAND INSULATOR I Application filed August 18, 1927. Serial No. 213,859.

The invention relates to insulators, particularly those of what may be called the post pedestal type embodying a plurality of porcelain sections surmounted by a metal The principal object of the invention is to improve the construction of the top shell or unit of such an insulator whereby the cap will be permitted to fit down more closely,

the mechanical strength-being thereby increased, and whereby there will be'ap interiitting effect strongly resisting torsional loadin it is well known that an insulator of the post pedestal type has its top shell carrying a cap formed with a plurality of holes for the accommodation or reception of cap screws or the like employed for mounting switch bases, bus bars and other elementsupon the insulator, the holes being located within thickened portions at the inside of the cap, I

the extra thickness of metal being necessary on account of the factthat the holes must be tapped. In the ordinary construction of the top shell these thickened portionsor lugs as they may be called cause the cap to extend upwardly to an excessive "extent, the over all height of the insulator being thereby increased without deriving'any advantage, and

. the mechanical strength being decreased in proportion to the increase in the moment arm in the event that a downward and lateral pressure is applied to the insulator.

It is with the above facts in view that I have designed the present invention which contemplates the provision'of a top shell appropriately recessed to accommodate the lugs or thickened portions of the cap in which the tapped holes are provided,'the recesses and 40 lugs interfitting and obviously resisting torsional strain, and the receptioir of the thick ened portions within the recesses resulting in a decrease in the height'of the insulator.

Another object is to provide a top-shell of this character which may be peripherally grooved, sanded or otherwise roughened to I insure a proper grip of the cement for securing the cap in place, there being no particular limitations in these details inasmuch as the constructed in accordance with my invening I have shown an insulator, or portion different methods mentioned are all old and well known.

An additional object is to provide an insulator top shell or unit which will cost no more than one of ordinary type to manufacture and which may be assembled with respect to the adjacent parts as simply and easily as one of conventional pattern.

To the attainment of the foregoing and other objects and advantages, the invention preferably consists in the details of construction and the arrangement and combination of parts to be hereinafter more fully described and claimed, and illustrated in the accom panying drawing in which:

Figure l is a View partly in side elevation' and partly in section showing an insulator of the post pedestal type having a top shell tion, v

Figure 2 is a fragmentary plan View of the top shell, and 1 Figure 3 is an inside plan view of the cap.

.Refer-ring more particularly to the draw thereof, includinga lower, section or unit 1 and a top shell 2, both being constructed of porcelain as is customary and both likewise possessing the usual characteristics or structural features in so far as skirts and other details are concerned. The lower section 1 is shown as recessed at 3 for mounting upon the usual pin, not shown, whichwould be cemented in place. The numeral i-designates the metal cap which is circular in shape and of a cup-like form to fit over the upstanding stem portion 5 of the top shell. In insu lators of this type the cap is provided with a plurality of holes 6, generally four in number, for-the reception of cap screws or the like used in In nting switch bases or other elements upo e insulator. The holes are necessarily ta ped and for this reason the cap is formed at-the holes with thickened portions. or lug s-7,which are on the underside of the There is nothing peculiar about the cap in so far as the present invention is con-' cerned and it is customary to secure the cap upon the upstanding stem portion 5 of the top shell by means of cement indicated at I 8, the inner. periphery of the cap being usually grooved and the outer periphery of the upstanding stem portion of the top shell being horizontally grooved, as illustrated in the drawing, or else sanded or otherwise roughened in order to insure a firm grip and strong joint between the cap and shell. The sanded construction is not illustrated inasmuch as it is so well known and as it is not any part of the invention.

In the ordinary construction of top shell the thickened portions or lugs 7 would come down upon the upper surface of the top shell and there is consequently quite a large mass of cement filling the space between the shell and cap. Thermally large masses of cement are objectionable and in the present instance such are eliminated. WVhat may be considered the feature of the present invention is.

the provision of a plurality of recesses 9 in .the top of the shell 2, these recesses being of at least slightly greater size than the thickened portions or lugs 7 so as to receive them readily and to leave sufficient space to be of:-

cupied by the cement. The exact shape of the recesses 9 may of course be varied as it is not an important consideration, but generally speaking they would probably be of the same or substantially the same contour as the lugs or thickened portions.

Assembly is effected in the ordinary manner and the insulator will have the same general appearance as those heretofore constructed except that the cap will come lower upon the top shell as the lugs or thickened portions are received withinthe recesses. The

I a I over all height is thus decreased with a corresponding increase in mechanical strength inasmuch as the moment arm is reduced. Furthermore the interfitting of the lugs and recesses will provide such an interlock as will positively resist torsional strains tending to rot-ate the cap with respect to the top shell. These advantageous-mechanical features are obtained without in any way detracting from the electrical strength or materially increas ing the cost of. production. From the foregoing it is believed that the construction, operation and advantages will be readily apparent to-one skilled in the art without further explanation.

\Vhile I have shown and described the preferrcd embodiment of the invention, it should be understood that the disclosure is merely an 'exemplification of the principles involved as the right is reserved to make all such changes in the details of construction as will widen the field of utility and increase the adaptability of the device provided such changes constitute no departure from the spirit of the invention or thescope of the claims hereunto appended.

Having thus described the invention, I

claim:

1. In a multi-part insulator, a. plurality of porcelain shells arranged in superposed relation, a cap for the topmost shell having relation, a cap for the topmost shell having a plurality of lugs on its inner underside, the topmostshell having recesses therein accommodating said lugs and conforming substantially thereto.

3. In an insulator, a plurality of dielectric shells and a metal cap mounted upon the topmost shell, the cap having thickened portions at its underside and tapped holes in said thickened portions, and said topmost shell having recesses in its top receiving said thickened portions.

4. In an insulator, a porcelain section having an upstanding stem portion formed in its top surface with a plurality of recesses, and a metal cap secured upon said stem portion and having the underside of its top provided -with dependingthickenedv portions consti- 

